Fuel pressure regulator buzzing . Tested 12 volts to regulator and it works ok . Connected to car and it buzzes and the engine light comes on and the two traction lights so we are in limp mode .this only happens in idle . Can anyone help . Thanks

what truck have you got bud ? what year ? which model ? auto/manual ? any other lights on ? have you read the fault codes ? any modifications done to the engine ? what were you doing when it first came on ?
all these answers will help others when they read this post